Re: 02 Mountaineer Clunk From Front End
First, be sure that the AWD isn't locked, where the transfer case 'locks' the front and rear axle together so that they turn at the same speed. This can lead to gear failure, irregular tire wear, and costly replacement of other components and bushings. It could be a number of things, from U joints, bent or worm tie rod; ball joints. You name it really.
If the gears are on their way out, they'll generally start to emit a shallow whining sound, and as the gears wear more, the noise will increase with speed. If you haven't done so in the last 30K, change the axle fluid out, front and rear, clean off the magnets and inspect the gears for any abnormal wear. I doubt you'll find any, but if the gear oil is dark and thick when it comes out, replacing it with a synthetic brand fluid should help increase mileage ever so slightly!
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!